Office air handling unit

ABSTRACT

An office air handling unit includes an intake, return and output system. The intake system transfers air from an external environment and through a preheating and cooling unit that regulates the temperature of the air entering the interior zone. The return system re-circulates air from the interior zone to the exterior zone through the use of a fan. The return system also regulates the temperature of the air entering the exterior zone by using a preheat unit and cooling unit. The output system allows for the transfer of air from the exterior zone to the external environment, re circulates the air back into the return system or re-circulates the air back into the intake system. The intake system allows for the transfer of air from the external environment to the return system to bypass the interior zone and provide fresh air to the exterior zone.

FIELD OF INVENTION

[0001] This invention relates to an air handling unit, and, more particularly, to an air handling unit for an office that circulates warmer air from an interior zone of the office to an exterior zone of the office while maintaining good indoor air quality.

BACKGROUND OF INVENTION

[0002] Modern office buildings include various types of air handling units that are used to regulate the temperature in interior and exterior zones of the office building. Interior zones are spaces that have no exterior windows or walls and exterior zones are located at the periphery of the building. Typically, interior zones require cooling for a substantial portion of the year due to the internal gain and retention of heat produced by people and the operation of equipment. In contrast, the exterior zones require heating during the winter and cooling during the summer. Therefore, during the winter months, simultaneous heating and cooling occurs in a typical office building.

[0003] In a prior air handling system for an office building, both the interior and the exterior zones receive the same supply air temperature. The supply air temperature is determined so as to satisfy the cooling requirement of the interior zone. A re-heat coil heats up the air supply to maintain room temperature for the exterior zone. The energy delivery efficiency, i.e. the ratio of the optimal heating and energy consumption to the actual heating and cooling energy consumption, for this type of system is often less than 0.7. In other words, the heating and cooling energy wastes are over 30% for a typical office building.

[0004] Another type of air handling unit that is commonly used in office buildings is a variable air volume (VAV) system. The VAV system includes two separate units used to separately regulate the temperatures of the interior and exterior zones. The unit used for cooling the exterior zone operates to provide the minimum fresh airflow to satisfy the indoor air quality requirement. When the outside air temperature is below +20° F. to 50° F., the mixing air temperature varies from 43° F. to 65° F. with a 30% minimum airflow. Consequently, the energy required to heat the exterior air for heating the exterior zones is almost the same as with the previous air handling unit, but the construction costs is increased significantly due to the use of two air handling units. Further, both of the prior art units occupy a large amount of space and reduce the amount of available office space.

[0005] Accordingly, there remains a need for an air handling unit which overcomes the above drawbacks and deficiencies. More specifically, there remains a need for an air handling unit that increases energy delivery efficiency. In addition, there remains a need for an air handling unit that decreases manufacturing costs. Further, there remains a need for an air handling unit that is relatively compact and does not occupy a large amount of space. The objective of this invention is to solve or substantially reduce the problems normally associated with known air handling units.

SUMMARY OF INVENTION

[0006] It is an object of the present invention to provide an air handling unit that increases energy delivery efficiency.

[0007] It is a further object of this invention to provide an air handling unit that decreases manufacturing costs.

[0008] It is an additional object of this invention to provide an air handling unit that is relatively compact and does not occupy a large amount of space.

[0009] According to the present invention, the foregoing and other objects are achieved by an air handling unit for use in an office building with interior and exterior zones. The air handling unit includes an intake, return and output system. The intake system includes a fan, a preheating unit and a cooling unit. The fan transfers air from an external environment to the interior zone. The preheat and cooling units regulate the temperature of the air entering the interior zone. The return system re-circulates air from the interior zone to the exterior zone through the use of a fan. The return system also includes a preheat unit and cooling unit that regulates the temperature of the air entering the exterior zone. The output system allows for the transfer of air from the exterior zone to the external environment, re-circulates the air back into the return system or re-circulates the air back into the intake system. The intake system allows for the transfer of air from the external environment to the return system to bypass the interior zone and provide fresh air for the exterior zone. In addition, the air handling unit can include a heat recovery unit that is coupled to either the intake or the output system. The heat recovery unit is used to extract heat energy from the air that is transferred through the intake or output system and use that energy to regulate the temperature of the interior and exterior zones.

[0010] Additional objects of invention, together with the advantages and novel features appurtenant thereto, will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following, or may be learned from the practice of the invention. The objects and advantages of the invention may be realized and attained by means and instrumentalities and combinations particularly pointed out in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] In the accompanying drawings which form a part of the specification and are to be read in conjunction therewith and in which like reference numerals are employed to indicate like parts in the various views:

[0012]FIG. 1 is a schematic drawing of the preferred embodiment of the present invention; and

[0013]FIG. 2 is a schematic drawing of an alternative embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0014] Referring to the drawings in greater detail, and initially to FIG. 1, an air handling unit embodying the principles of this invention is broadly designated in the drawings by reference numeral 10. Unit 10 is adapted to be installed in an office building 11 that includes an interior zone 12 and an exterior zone 14. While unit 10 is described as being installed in an office building, it will be appreciated that unit 10 could be used in residential homes, vehicles or any other type of enclosure having interior and exterior zones. Unit 10 operates to circulate air through internal and external zones 12, 14 through the use of an intake system 16, a return system 18 and an output system 20 which will be more fully described below.

[0015] As seen best seen in FIG. 1, intake unit 16 is used to transfer air from an external environment 22 to interior zone 12 through an air duct or passageway 24. At the point where air enters duct 24 from external environment 22, intake unit 16 includes an insertion type wet and dry-bulb air temperature sensors 26, 28. An air infilter 30 is mounted in duct 24 and positioned within duct 24 after sensors 26, 28 to remove particulate matter suspended in the air as it travels from external environment 22. An air pressure differential sensor 32 is coupled to the upstream and downstream sides of filter 30 to monitor the pressure drop as the air passes through filter 30. If sensor 32 indicates an unacceptable pressure drop, a user has a sufficient amount of time to correct the problem without having to shut down unit 10 for a long period of time.

[0016] A heat recovery unit 33 may be placed between filter 30 and sensor 34 to remove heat energy from the air being taken in from external environment 22 and return that energy back to interior and exterior zones 12. The application of heat recovery unit 33 is particularly applicable in a situation when interior zone 12 needs to be cooled and exterior zone 14 needs to be heated. As the air is drawn in from external environment 22, heat recovery unit 33 takes heat energy from the air thereby decreasing the temperature of the air transferred to interior zone 12. The heat energy that is removed from the air is used in heating the air entering external zone 14. Therefore, the process of cooling internal zone 12 and heating exterior zone 14 is more efficient through the use of heat recovery unit 33. The structure of heat recovery unit 33 is well known in the art and need not be discussed any further.

[0017] A cross-overtype dry-bulb air temperature sensor 34 is adapted to monitor the air after it travels through heat recover unit 33. A damper 36 is mounted within duct 24 to allow for the selective adjustment of the downstream air flow rate. Damper 36 can be adjusted to an open, partially open or closed position to allow full air flow, partial air flow or no air flow so that air is prevented from flowing downstream of damper 36. A supply air fan 38 is mounted within duct 24 to increase the air flow velocity through a preheating and cooling unit 40, 42. Upstream of preheat unit 40 is a cross-over type sensor 44 for measuring the dry-bulb temperature of the air prior to the air passing through preheating unit 40. Preheat unit 40 operates to heat the air passing through duct 24 when the selected temperature in interior zone 12 is higher than the air temperature reading by an insertion type dry-bulb sensor 45 that measures the actual air temperature within interior zone 12. Preheat unit 40 will continue to raise the temperature of the air passing through duct 24 until interior zone 12 reaches the selected temperature. If the selected temperature of interior zone 12 is lower than the temperature of the air within interior zone 12, then preheat unit 40 is not activated and the air passes through duct 24 without being heated. An air pressure differential sensor 46 is coupled to the upstream and downstream sides of preheat unit 40 to monitor the pressure drop after the air passes through preheat unit 40. The air is then measured by cross-over type dry-bulb air temperature sensors 48, 50 before and after entering cooling unit 42. Cooling unit 42 includes cooling coils that are used to decrease the temperature of the air entering interior zone 12. A sensor 52 takes an air pressure reading just prior to entering interior zone 12. Generally, sensor 45 measures the air temperature within interior zone 12 to determine whether heating or cooling is necessary to achieve the temperature selected for interior zone 12.

[0018] Return system 18 includes a duct or passageway 56 that is used to re-circulate air from interior zone 12 and transfer it to exterior zone 14. A pressure sensor 58 and an air flow rate sensor 60 are used to monitor the air as it leaves interior zone 12. At that point, a return fan 62 moves the air leaving interior zone 12 through the use of a damper 64. Following damper 64, another return fan 66 is mounted within duct 56 and operates to increase the flow rate of the air passing through preheating and cooling units 68, 70. The preheating and cooling units 68, 70 are arranged in a similar fashion to those mounted in the intake system 16. Specifically, upstream of preheat unit 68 is a cross-over type sensor 72 for measuring the dry-bulb temperature of the air prior to the air passing through preheating unit 68. Preheat unit 68 operates to heat the air passing through duct 56 when the selected temperature in exterior zone 14 is higher than the air temperature reading by an insertion type dry-bulb sensor 73 that measures the air temperature within exterior zone 14. Cooling unit 70 will continue to lower the temperature of the air passing through duct 56 until exterior zone 14 reaches the selected temperature. If the selected temperature of exterior zone 14 is lower than the temperature of the air within exterior zone 14, then preheat unit 68 is not activated and the air passes through duct 56 without being heated. An air pressure differential sensor 74 is coupled to the upstream and downstream sides of preheat unit to monitor the pressure drop after the air passes through preheat unit 74. The air is then measured by cross-over type dry-bulb air temperature sensors 76, 78 before and after entering cooling unit 70. Cooling unit 70 includes cooling coils that are used to decrease the temperature of the air entering exterior zone 14. A sensor 80 takes an air pressure reading just prior to entering exterior zone 14. Sensor 73 measures the air temperature to determine whether heating or cooling is needed to meet the temperature selected for exterior zone 14.

[0019] Output system 20 includes a duct or passageway 84 that is used to transfer air from exterior zone 14 and return it to the external environment 22. A pressure sensor 86 and an air flow rate sensor 88 are used to monitor the air as it leaves exterior zone 14. A supply fan 90 increases the flow velocity of the air leaving exterior zone 14 through the use of a damper 92. Damper 92 is mounted within duct 84 and can be opened to allow air to be released to external environment 22, closed to re-circulate the air back into unit 10, or partially opened to allow some air to escape and some air to re-circulate back through unit 10.

[0020] A heat recovery unit 94 can be installed in the output system 20 to remove heat energy from the air being removed from unit 10 and return that energy back to interior and exterior zones 12. Heat recovery unit 94 can be used exclusively or in conjunction with heat recovery unit 33 that is installed in the intake system 16. In either case, units 33, 94 operate in a similar fashion, the only difference being their location. Unit 94 operates to remove heat energy from the air that is removed from exterior zone 14 and transfer the recovered energy back into heating interior and exterior zones 12, 14. The structure of the heat recovery unit 94 is well known in the art and will not be discussed any further.

[0021] A bypass extension 96 is a duct or passageway that is used to transfer air from intake system 16 directly to return system 18. Extension 96 couples duct 24 with duct 56 to provide fresh air directly to exterior zone 14 without the air having to pass through interior zone 12. A damper 98 is used to completely open extension 96 to allow for a fresh air to flow in return system 18, close extension 96 to prevent any fresh air from being transferred directly to exterior zone 14 or partially open damper 98 to allow for some transfer of fresh air to exterior zone 14.

[0022] First and second ducts or passageways 100, 102 operate to re-circulate the air leaving exterior zone 14 and send that air back into return system 18 and intake system 16 respectively. The re-circulation of the air back into systems 16, 18 decrease the amount of energy needed by the preheating and cooling units 40, 42, 68, 70 to heat and cool the air flowing back into the exterior and interior zones 14, 12. Specifically, the air being re-circulated has already been heated or cooled by units 40, 42, 68, 70 before entering zones 12, 14. Therefore, the amount of energy it would take to heat or cool the re-circulated air would be less than heating or cooling air coming through units 40, 42, 68, 70 from external environment. The re-circulation process provides for a more efficient means for heating and cooling interior and external zones 12, 14. Dampers 104, 106 are used to selectively control the amount of re-circulation that occurs in unit 10.

[0023] In operation, unit 10 operates to draw air from the external environment 22 through the operation of fan 38 so long as damper 36 is fully or partially open. As air flows into intake unit 16, sensors 26, 28 measure the wet and dry-bulb temperature and the particulate matter in the air is taken out of the air by filter 30. Heat recovery unit 33 recovers heat energy from the air stream and sensor 34 takes another dry-bulb temperature reading. Depending on whether the temperature of the air in interior zone 12 needs to be raised or lowered, the preheat or cooling unit will be activated to adjust the air temperature accordingly. The air flows into interior zone 12 at a selected temperature.

[0024] If damper 64 is fully or partially opened, air from interior zone 12 is transferred through duct 56 through the operation of fans 62, 66. Sensors 72, 76 take air temperature measurements and compare the temperature reading by sensor 73 within interior zone 12 to determine whether the air flowing through duct 56 needs to be heated or cooled. Depending on the measurements taken, either preheat or cooling unit 68, 70 will operate to adjust the air temperature selected for exterior zone 14.

[0025] Air from exterior zone 14 is drawn into output system 20 by fan 90. At this point the air traveling through duct 84 has three alternative routes. If damper 92 is completely or partially open, air will continue to flow through duct 84, passing through heat recovery unit 94 and then out to external environment 22. If damper 102 is open, air flowing through duct 84 will pass through duct 100 and re-circulate back into return unit 20 and eventually return to the exterior zone. Finally, if damper 106 is open, the air flowing through duct 84 will pass through duct 104 and re-circulate back into intake unit 16 and eventually return to the interior zone 12. It should be understood that unit 10 is capable of achieving various types of re-circulation patterns by selectively adjusting each of the dampers in units 10, 110 in different combinations.

[0026] Fresh air is directly transferred from external environment 22 to exterior zone 14 by opening damper 98 which allows the flow of air through duct 96. Fan 66 assists in producing the desired air flow rate through duct 96. Unit 10 allows for adequate fresh air to be transferred to both the interior and exterior zone. When exterior zone 14 needs to be heated, interior zone 14 may receive up to 100% outside air. Since adequate fresh air can be transferred to each zone 12, 14, the carbon dioxide level will satisfy the industry standard.

[0027] When the ambient air temperature lower than 58° F. or the enthalpy of the outside air is lower than room air enthalpy 25 Btu/lbm, the mixed air temperature is maintained at 53° F. for the interior section. The air from external environment 22 to interior zone 12 is significantly higher than the design flow. The mixed air temperature to exterior zone 14 may vary from 55° F. to 75° F. depending on the selected comfort temperature of exterior zone 14. Since the external air intake of internal zone 12 is significantly higher than the minimum design flow, both interior and exterior zones 12, 14 have good indoor air quality.

[0028] Unit 10 can still use free cooling for interior zone 12 and save the heating energy requirement for exterior section 14 when outside air temperature is very low. For example, when the external air temperature is −20° F., the outside air intake to interior zone 12 will be 20% of the total airflow. If exterior zone 14 has the same floor area as interior zone 12, the supply air temperature to exterior zone 14 can be as high as 74° F. by using 100% return air from interior zone 12 with satisfactory air quality. Unit 10 is functions the best in a climate where economizer has the most potential, but it should be understood that unit 10 can be used in most any climate.

[0029] As best seen in FIG. 2, an air handling unit embodying an alternative embodiment of the present invention is broadly designated in the drawings by reference numeral 110. Unit 110 is also adapted to be installed in a building 11, but has a simplified construction when compared to the preferred embodiment. Unit 110 regulates and handle the air flowing through interior and exterior zones 112, 114. Unit 110 is preferably used in a situation where the floor area ratio between interior and exterior zone 112, 114 is higher than 2 to 1. This simplified construction will further decrease the manufacturing costs compared to the prior art.

[0030] Just as in the preferred embodiment, unit 110 includes a intake system 116, a return system 118 and an output system 120. Intake system 116 is substantially the same as in the preferred embodiment and will not be discussed any further. In addition, a bypass extension duct or passageway 119 operates the same as in the preferred embodiment and will also not be discussed any further. As for return and output systems 118, 120, the components of each are substantially the same as in the preferred embodiment and are labeled as such, but the duct configuration is simplified and will be explained in more detail.

[0031] Return system 118 includes a ducts or passageways 122,123 that transfers air from interior zone and exterior zone 114 and re-circulates the air back to exterior zone 114. Duct 122 extends between interior and exterior zones 112, 114 and allows air coming from zones 112, 114 to converge toward each other. Duct 123 extends from duct 122 and back to exterior zone 114. Duct 123 allows the air coming from the zones 112, 114 to mix as the air is re-circulated back to exterior zone 114. A damper 124 operates to control the airflow through duct 123. When air is transferred by output system 120 from exterior zone 114, the air moves through the same duct 122 used to transfer the air in the return system 118, thereby mixing the air coming out of both interior zone 112 and exterior zone 114. In the preferred embodiment as previously described, the re-circulation duct 100 allowed for selectively mixing of air traveling through output system 20 and return system 18 by adjusting damper 102. In this embodiment, mixing of the air occurs continuously so long as air is moving in exterior zone 114 through the use of return system 118 and out of exterior zone 114 through duct 122.

[0032] After the mixing the air coming out of both interior and exterior zones 112, 114, the air can move in three directions from point 126 depending on which dampers are open. If damper 124 is open, air will move through duct 122 and flow into exterior zone 114. If damper 128 is open, air will flow through an output duct or passageway 130 and to the external environment 22. Finally, if damper 132 is open, air will move through duct 134 and re-circulate back into intake system 116.

[0033] Constructed and operated as previously described, the invention provides an office air handing unit 12 that increases energy delivery efficiency by re-circulating air from interior zone 12 to exterior zone 14. Unit 10 occupies less mechanical room space and the cost of construction is lower compared to prior art air handling units. In addition, the alternative embodiment further decreases the systems cost due to its simplified construction.

[0034] From the foregoing, it will be seen that this invention is one well-adapted to attain the ends and objects hereinabove set forth together with other advantages which are obvious and inherent to the device. It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and within the scope of the claims. Since many possible embodiments may be made of the invention without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in accompanying drawings is to be interpreted as illustrative and not in a limiting sense. 

I claim:
 1. An air handling unit for use in a building having an interior and exterior zones, wherein said unit comprises: an intake system coupled to the interior zone; an output system coupled to the exterior zone; a return system coupled between the interior and exterior zones; wherein said intake system transfers air from an external environment to the interior zone; wherein said return system transfers air from the interior zone to the exterior zone; and wherein said output system transfers air from the exterior zone to the external environment.
 2. The unit as recited in claim 1, wherein said intake system includes a first supply fan.
 3. The unit as recited in claim 1, wherein said intake system includes a preheating unit and a cooling unit.
 4. The unit as recited in claim 1, wherein said intake system includes a heat recovery unit.
 5. The unit as recited in claim 1, wherein said intake system includes a filter.
 6. The unit as recited in claim 1, wherein said return system includes a first return fan, a flow rate sensor and a pressure sensor.
 7. The unit as recited in claim 1, wherein said return system includes a preheating unit and a cooling unit.
 8. The unit as recited in claim 1, wherein said output system includes a second return fan, a flow rate sensor and a pressure sensor.
 9. The unit as recited in claim 1, wherein said output system includes a heat recovery unit.
 10. The unit as recited in claim 1, wherein said intake system is further coupled to said return system.
 11. The unit as recited in claim 10, wherein said return system includes a second supply fan.
 12. The unit as recited in claim 1, wherein said output system is coupled to said return system, wherein the air moving through said output system is re-circulated to said return system and back into the exterior zone.
 13. The unit as recited in claim 12, wherein said intake system is coupled to said output system at a location that would allow air from said input system to mix with the air in said output system before being re-circulated to the exterior zone.
 14. A method of handling air for use in a building having interior and exterior zones, said method comprising the steps of: supplying air from an external environment to the interior zone; re-circulating the air from the interior zone to the exterior zone; and removing the air from the exterior zone to the external environment.
 15. The method as recited in claim 14, further comprising the step of allowing for the transfer of air from the external environment to the exterior zone.
 16. The method as recited in claim 14, further comprising the step of allowing for the transfer of air from the exterior zone to be re-circulated back into the exterior zone.
 17. The method as recited in claim 14, further comprising the step of allowing for the transfer of air from the exterior zone to be re-circulated back into the interior zone.
 18. An air handling unit for use in a building having an interior and exterior zones, wherein said unit comprises: an intake system coupled to the interior zone; a return system coupled between the exterior and interior zones; an output system coupled to said return system; wherein said intake system transfers air from an external environment to the interior zone; wherein said return system combines air from the exterior and interior zones and transfers the air back to the exterior zone; and wherein said output system transfers air from said return system zone to the external environment.
 19. The unit as recited in claim 18, wherein said intake system includes a first supply fan.
 20. The unit as recited in claim 18, wherein said intake system includes a preheating unit and a cooling unit.
 21. The unit as recited in claim 18, wherein said intake system includes a heat recovery unit.
 22. The unit as recited in claim 18, wherein said intake system includes a filter.
 23. The unit as recited in claim 18, wherein said return system includes a return fan, a flow rate sensor and a pressure sensor.
 24. The unit as recited in claim 18, wherein said return system includes a preheating unit and a cooling unit.
 25. The unit as recited in claim 18, wherein said output system includes a heat recovery unit.
 26. The unit as recited in claim 18, wherein said intake system is coupled to said return system, wherein said air from said intake system moves directly into said return system without moving though the interior zone.
 27. The unit as recited in claim 26, wherein said return system includes a second supply fan.
 28. The unit as recited in claim 18, wherein said return system is coupled to said intake system, wherein the air can be transferred from said return system and re-circulated through said intake system.
 29. The unit as recited in claim 18, wherein said return system includes: a first passageway extending between interior and exterior zones; a second passageway that extends from said first passageway and back to the exterior zone; and wherein the air flowing through said first passageway from the interior and exterior zones mix in said second passageway and re-circulates to the exterior zone.
 30. A method of handling air for use in a building having interior and exterior zones, said method comprising the steps of: supplying air from an external environment to the interior zone; re-circulating the air from the interior zone to the exterior zone; removing the air from the exterior zone; re-circulating the air removed from the exterior zone back into the exterior zone; and removing the air from the exterior zone into the external environment.
 31. The method as recited in claim 29, further comprising the step of mixing the air removed from the exterior zone with the air re-circulating from the interior zone.
 32. The method as recited in claim 29, further comprising the step of removing air from the internal environment to the external environment.
 33. The method as recited in claim 29, further comprising the step of supplying air from the external environment to the exterior zone.
 34. The method as recited in claim 29, further comprising the step of re-circulating air from the exterior zone to the interior zone. 